Sung-Heui Shin

Publications of Sung-Heui Shin

• Cyclic AMP-receptor protein activates aerobactin receptor IutA expression in Vibrio vulnificus.

  Authors: Choon-Mee Kim, Seong-Jung Kim, Sung-Heui Shin

  Journal of microbiology (Seoul, Korea). 04/2012; 50(2):320-5.

  The ferrophilic bacterium Vibrio vulnificus can utilize the siderophore aerobactin of Escherichia coli for iron acquisition via its specific receptor IutA. This siderophore piracy by V. vulnificusThe ferrophilic bacterium Vibrio vulnificus can utilize the siderophore aerobactin of Escherichia coli for iron acquisition via its specific receptor IutA. This siderophore piracy by V. vulnificus may contribute to its survival and proliferation, especially in mixed bacterial environments. In this study, we examined the effects of glucose, cyclic AMP (cAMP), and cAMP-receptor protein (Crp) on iutA expression in V. vulnificus. Glucose dose-dependently repressed iutA expression. A mutation in cya encoding adenylate cyclase required for cAMP synthesis severely repressed iutA expression, and this change was recovered by in trans complementing cya or the addition of exogenous cAMP. Furthermore, a mutation in crp encoding Crp severely repressed iutA expression, and this change was recovered by complementing crp. Accordingly, glucose deprivation under iron-limited conditions is an environmental signal for iutA expression, and Crp functions as an activator that regulates iutA expression in response to glucose availability.

• Molecular typing of an Acinetobacter baumannii outbreak based on integron-gene cassette array-PCR

  Authors: Bidur Prasad Chaulagaina, Dipendra Raj Pandeya, Dong-Min Kim, Jong-Hee Shin, Joong-Ki Kook, Sung-Heui Shin, Dae-Soo Moong, Young-Jin Park, Sook Jin Jang

  Biomedical Research. 01/2011; Vol. 22(1):2011-01 - 2011-03.

  A total of 62 Acinetobacter baumannii isolates including 29 imipenem resistant, 23 imipenem susceptible and 10 environmental isolates were analyzed based on integron and integron gene cassette arrayA total of 62 Acinetobacter baumannii isolates including 29 imipenem resistant, 23 imipenem susceptible and 10 environmental isolates were analyzed based on integron and integron gene cassette array (I-GCA) PCR and DNA sequences. Two types of class 1 integron were found based on their cassette arrays. The integron class 1 with a 2.6 kb size (Int1-A ) has the cassette order of aaC(6’)-Im followed by another gene cassette aadA1 disrupted by IS26 transposase, while the another class 1 integron with 2.8 kb size (Int1-B) has the gene cassette order of aacC1 followed by orfX, orfX’, IS 26 transposase and aadA1. PCR mapping detect the distribution of such integron types within the isolates. Integron gene cassette array PCR (I-GCA PCR) typing gave 20 profiles while PFGE typing gave 18 profiles with 16 types and 2 sub-types. The major profile I of I-GCA PCR equivalent to profile A of PFGE was the dominant profile covering most of the clinical and environmental imipenem resistant isolates while the second largest profile XII of I-GCA PCR or profile M of PFGE was found in the imipenem susceptible isolates. Both integron types Int1-A and Int1-B were mostly restricted to imipe-nem resistant outbreak strains of the major profile I of I-GCA PCR or profile A of PFGE. I-GCA PCR based typing gave similar result to that of PFGE by sharing all the imipenem resistant strains of distinct profile I of I-GCA PCR in the profile A of PFGE which was responsible for the present A. baumannii outbreak. These results indicate that I-GCA PCR alone or coupled with other typing method would be a rapid tool for epidemiological study for bacteria that bear integron.

• Modulation of iron-uptake systems by a mutation of luxS encoding an autoinducer-2 synthase in Vibrio vulnificus.

  Authors: Choon Mee Kim, Sung Heui Shin

  Biological & pharmaceutical bulletin. 01/2011; 34(5):632-7.

  Vibrio vulnificus possesses multiple iron-uptake systems which are mediated by VuuA (vulnibactin receptor), IutA (aerobactin receptor) and HupA (heme receptor). In this study, we determined theVibrio vulnificus possesses multiple iron-uptake systems which are mediated by VuuA (vulnibactin receptor), IutA (aerobactin receptor) and HupA (heme receptor). In this study, we determined the effect of a mutation of luxS encoding autoinducer-2 (AI-2) synthase on the expressions of the three receptors. A mutation and an in trans complementation of luxS did not affect the growing ability of V. vulnificus in iron-deficient conditions. Nevertheless, the luxS mutation slightly decreased vuuA expression, but slightly increased iutA and hupA expressions in the transcriptional reporter assay or Western blot analysis. These changes were all recovered by the luxS complementation. These results suggest that AI-2-mediated quorum sensing system may be involved in the fine modulation of V. vulnificus iron-uptake systems, positively affecting vuuA expression but negatively affecting iutA and hupA expressions.

• Differences in clinical features according to Boryoung and Karp genotypes of Orientia tsutsugamushi.

  Authors: Dong-Min Kim, Na Ra Yun, Ganesh Prasad Neupane, Sung Heui Shin, So Yeon Ryu, Hee Jung Yoon, Seong Heon Wie, Woo Jin Kim, Chang Youl Lee, Jong Soo Choi, Tae Young Yang

  PloS one. 01/2011; 6(8):e22731.

  Scrub typhus is an infectious disease caused by Orientia tsutsugamushi. The differences in virulence of O. tsutsugamushi prototypes in humans are still unknown. We investigated whether there are anyScrub typhus is an infectious disease caused by Orientia tsutsugamushi. The differences in virulence of O. tsutsugamushi prototypes in humans are still unknown. We investigated whether there are any differences in the clinical features of the Boryoung and Karp genotypes. Patients infected with O. tsutsugamushi, as Boryoung and Karp clusters, who had visited 6 different hospitals in southwestern Korea were prospectively compared for clinical features, complications, laboratory parameters, and treatment responses. Infected patients in the Boryoung cluster had significantly more generalized weakness, eschars, skin rashes, conjunctival injection, high albumin levels, and greater ESR and fibrinogen levels compared to the Karp cluster. The treatment response to current antibiotics was significantly slower in the Karp cluster as compared to the Boryoung cluster. The frequency of occurrence of eschars and rashes may depend on the genotype of O. tsutsugamushi.

• Regulation of the Vibrio vulnificus vvpE expression by cyclic AMP-receptor protein and quorum-sensing regulator SmcR.

  Authors: Choon-Mee Kim, Sung-Heui Shin

  Microbial pathogenesis. 12/2010; 49(6):348-53.

  In Vibrio vulnificus, cAMP-receptor protein (CRP) and the quorum-sensing regulator SmcR are simultaneously and cooperatively required for the metalloprotease vvpE gene expression, rather thanIn Vibrio vulnificus, cAMP-receptor protein (CRP) and the quorum-sensing regulator SmcR are simultaneously and cooperatively required for the metalloprotease vvpE gene expression, rather than sequentially in a regulatory cascade. However, this study shows a new temporal and functional sequence between the two factors in regulating vvpE expression. A crp mutation inhibited vvpE expression with growth impairment from early stage. In contrast, a smcR mutation inhibited vvpE expression only at the late stage with no effect on growth. A crp-smcR double mutation severely inhibited vvpE expression with growth impairment from early stage. The inhibited vvpE expression was restored only at the early stage by a crp single complementation, but not at all by a smcR complementation. These results indicate that CRP functions as an essential activator, whereas SmcR functions in the presence of CRP for full vvpE expression.

• Virulence characteristics of sucrose-fermenting Vibrio vulnificus strains.

  Authors: Seong-Jung Kim, Choon-Mee Kim, Sung-Heui Shin

  The Korean journal of laboratory medicine. 10/2010; 30(5):507-10.

  We identified 6 sucrose-fermenting Vibrio vulnificus strains and examined their virulence characteristics. They were all encapsulated, motile, capable of producing toxins and utilizingWe identified 6 sucrose-fermenting Vibrio vulnificus strains and examined their virulence characteristics. They were all encapsulated, motile, capable of producing toxins and utilizing transferrin-bound iron, cytotoxic to cultured cells, and virulent enough to kill mice. They could be definitely identified only by genetic identification methods such as PCR, and not by conventional culture-based identification methods such as API 20E (bioMérieux, France). These results indicate that it is essential to adopt genetic approaches as early as possible in order to avoid misdiagnosis of such strains, especially in clinical situations.

• Prevalence and spread of integron-IS26 in imipenem-resistant Acinetobacter baumannii clinical isolates in South Korea.

  Authors: Ok Yeon Jeoung, Sook Jin Jang, Xue Min Li, Geon Park, Dong Eun Yong, Jung Oak Kang, Sun Hoe Koo, Won Yong Kim, Eui-Chong Kim, Yeon-Joon Park [......] Tae Yeal Choi, Ji-Hyun Cho, Seok Hoon Jeong, Seong Geon Hong, Jongwook Lee, Dong-Min Kim, Chulhun L Chang, Sung-Heui Shin, Dae Soo Moon, Young Jin Park

  International journal of antimicrobial agents. 10/2009;

• Iron Differentially Regulates Gene Expression and Extracellular Secretion of Vibrio vulnificus Cytolysin-Hemolysin.

  Authors: Choon-Mee Kim, Yoon-Young Chung, Sung-Heui Shin

  The Journal of infectious diseases. 09/2009; 200(4):582-9.

  In a previous study, we showed that Vibrio vulnificus is a ferrophilic bacterium that requires high levels of available iron for growth. In the present study, we show that iron stimulates, in anIn a previous study, we showed that Vibrio vulnificus is a ferrophilic bacterium that requires high levels of available iron for growth. In the present study, we show that iron stimulates, in an unusual manner, the production of cytolysin-hemolysin (VvhA), the most potent exotoxin produced by V. vulnificus. The vvhA gene possesses a putative ferric uptake regulator (Fur)-binding box in the regulatory region, andvvhA transcription was repressed by iron and de-repressed by fur mutation. However, extracellular secretion of VvhA was conversely increased by iron. Iron increased transcription of pilD, which encodes PilD, a component of the type II general secretion system responsible for extracellular VvhA secretion. These results indicate that iron increases extracellular VvhA secretion via the type II general secretion system, although it can repress vvhA transcription via Fur.

• Effect of iron-chelator deferiprone on the in vitro growth of staphylococci.

  Authors: Choon-Mee Kim, Sung-Heui Shin

  Journal of Korean medical science. 05/2009; 24(2):289-95.

  The standard iron-chelator deferoxamine is known to prevent the growth of coagulase-negative staphylococci (CoNS) which are major pathogens in iron-overloaded patients. However, we found thatThe standard iron-chelator deferoxamine is known to prevent the growth of coagulase-negative staphylococci (CoNS) which are major pathogens in iron-overloaded patients. However, we found that deferoxamine rather promotes the growth of coagulase-positive Staphylococcus aureus. Accordingly, we tested whether deferiprone, a new clinically-available iron-chelator, can prevent the growth of S. aureus strains as well as CoNS. Deferiprone did not at least promote the growth of all S. aureus strains (n=26) and CoNS (n=27) at relatively low doses; moreover, it could significantly inhibit the growth of all staphylococci on non-transferrin-bound-iron and the growth of all CoNS on transferrin-bound iron at relatively high doses. At the same doses, it did not at least promote the growth of all S. aureus strains on transferrin-bound-iron. These findings indicate that deferiprone can be useful to prevent staphylococcal infections, as well as to improve iron overload, in iron-overloaded patients.

• Identification of an atypical integron carrying an IS26-disrupted aadA1 gene cassette in Acinetobacter baumannii.

  Authors: Hu Lin Han, Sook Jin Jang, Geon Park, Joong-Ki Kook, Jong Hee Shin, Sung-Heui Shin, Dong-Min Kim, Ji Seon Cheon, Dae Soo Moon, Young Jin Park

  International journal of antimicrobial agents. 09/2008; 32(2):165-9.

  An unusual class 1 integron was identified that carries an IS26-disrupted aadA1 gene cassette (designated as 'integron-IS26') in an imipenem-resistant Acinetobacter baumannii (IRAB) outbreak strain.An unusual class 1 integron was identified that carries an IS26-disrupted aadA1 gene cassette (designated as 'integron-IS26') in an imipenem-resistant Acinetobacter baumannii (IRAB) outbreak strain. DNA sequencing revealed that integron-IS26 contained two gene cassettes, the aac(6')-Im cassette and a peculiar aadA1 cassette that was disrupted by IS26 (disrupted aadA1 cassette). Southern blotting localised integron-IS26 to the chromosome. Nested polymerase chain reaction (PCR) was performed to define the frequency of integron-IS26 in five groups of bacteria. Nested PCR identified integron-IS26 in 19 (73.1%) of 26 clinical outbreak strains of IRAB, 10 (100%) of 10 IRAB isolated from environmental cultures, 3 (13.0%) of 23 imipenem-susceptible A. baumannii (ISAB) non-outbreak strains, 1 (3.6%) of 28 netilmicin- and tobramycin-resistant A. baumannii and none of the netilmicin- and tobramycin-resistant Pseudomonas aeruginosa. In conclusion, we have identified a novel class I integron that carries the aac(6')-Im cassette and an IS26-disrupted copy of aadA1 (integron-IS26) in most IRAB outbreak strains and in a few ISAB non-outbreak control strains. Integron-IS26 is located chromosomally.

• Two forms of Vibrio vulnificus metalloprotease VvpE are secreted via the type II general secretion system.

  Authors: Jong Park, So Yeon Ryu, Choon-Mee Kim, Sung-Heui Shin

  Journal of microbiology (Seoul, Korea). 07/2008; 46(3):338-43.

  Vibrio vulnificus has been known to secrete one form of metalloprotease VvpE (45 kDa) that is cleaved to 34 kDa-VvpE and 11 kDa-C-terminal propeptide via extracellular autoproteolysis. However, weVibrio vulnificus has been known to secrete one form of metalloprotease VvpE (45 kDa) that is cleaved to 34 kDa-VvpE and 11 kDa-C-terminal propeptide via extracellular autoproteolysis. However, we found that extracellular secretion of both the 34 and 45 kDa forms of VvpE began in the early growth phase; moreover, 34 kDa-VvpE existed as the major form in V. vulnificus cell lysates and culture supernatants. In addition, extracellular secretion of both 34 and 45 kDa-VvpE was blocked by mutation of the pilD gene, which encodes for the type IV leader peptidase/N-methyltransferase of the type II general secretion system, and the blocked VvpE secretion was recovered by in trans-complementation of the wild-type pilD gene. These results indicate that 34 kDa-VvpE is the major form secreted along with 45 kDa-VvpE from the early growth phase via the PilD-mediated type II general secretion system.

• Hyperthermia switches glucose depletion-induced necrosis to apoptosis in A549 lung adenocarcinoma cells.

  Authors: Song Iy Han, Hong-Quan Duong, Jeong Eun Choi, Tae-Bum Lee, Cho Hee Kim, Su Yeon Lee, Hyun Min Jeon, Sung-Heui Shin, Sung-Chul Lim, Ho Sung Kang

  International journal of oncology. 05/2008; 32(4):851-60.

  Both cellular and clinical studies have shown that hyperthermia is one of the most potent sensitizers for the action of ionizing radiation. Although hyperthermic improvement in clinical outcome isBoth cellular and clinical studies have shown that hyperthermia is one of the most potent sensitizers for the action of ionizing radiation. Although hyperthermic improvement in clinical outcome is suggested to be linked to its ability to induce cell cycle arrest and apoptosis, and to activate the immune system and to cause increases in blood flow and tumor oxygenation, the mechanism behind this is still unclear. Previously, we demonstrated that glucose deprivation (GD), a common characteristic of the tumor microenvironment, induced necrosis, which is implicated in tumor progression and aggressiveness, through the production of reactive oxygen species (ROS) in A549 lung carcinoma cells. We examined the effects of heat shock on ROS production and necrosis in response to GD. Here we show that mild, but not harsh, heat shock prevented GD-induced necrosis and switched the cell death mode to apoptosis in A549 cells through the ERK1/2 pathway that could suppress GD-induced CuZnSOD release and ROS production. These results demonstrate that contrary to severe heat shock, mild heat shock has the ability to decrease oxidative stress in cells, thereby causing the cell death mode switch from tumor promoting necrosis to tumor suppressive apoptosis, which may contribute to its anti-neoplastic activities.

• A widespread deferoxamine-mediated iron-uptake system in Vibrio vulnificus.

  Authors: Choon-Mee Kim, Yong-Jin Park, Sung-Heui Shin

  The Journal of infectious diseases. 12/2007; 196(10):1537-45.

  Vibrio vulnificus can use the standard iron chelator deferoxamine (Desferal) for efficient iron-uptake via the specific receptor DesA, which is encoded by desA. We investigated the ubiquity of theVibrio vulnificus can use the standard iron chelator deferoxamine (Desferal) for efficient iron-uptake via the specific receptor DesA, which is encoded by desA. We investigated the ubiquity of the deferoxamine-mediated iron-uptake system in V. vulnificus strains and the potential risk of the system. By polymerase chain reaction (PCR), desA was found in 10 of 10 clinical strains and in 9 of 10 environmental strains, and their growth was stimulated by deferoxamine. By reverse-transcriptase PCR, desA was expressed only under iron-limited conditions containing deferoxamine. V. vulnificus growth in the presence of deferoxamine was suppressed by desA mutation, and the suppressed growth was recovered by desA complementation. Deferoxamine stimulated V. vulnificus growth in iron-limited in vitro and ex vivo backgrounds containing transferrin-bound iron. Overall, V. vulnificus can use transferrin-bound iron via the widespread deferoxamine-mediated iron-uptake system; this cautions that deferoxamine therapy in patients with iron overload may increase the risk of fatal infections caused by V. vulnificus.

• Production of Vibrio vulnificus metalloprotease VvpE begins during the early growth phase: usefulness of gelatin-zymography.

  Authors: Choon-Mee Kim, Sang-Mee Kang, Ho-Jong Jeon, Sung-Heui Shin

  Journal of microbiological methods. 08/2007; 70(1):96-102.

  Recent studies have demonstrated that expression of the vvpE gene begins during the early growth phase albeit at low levels. However, we found that the traditional protease assay method that is usedRecent studies have demonstrated that expression of the vvpE gene begins during the early growth phase albeit at low levels. However, we found that the traditional protease assay method that is used to measure caseinolytic activity in culture supernatants is not suitable for the measurement of extracellular VvpE that is produced at low levels during the early growth phase. By using gelatin-zymography in place of the protease assay, we could specifically detect only VvpE of several proteases produced by Vibrio vulnificus. Moreover, we could sensitively measure VvpE produced at low levels during the early growth phase, which was consistent with transcription of the vvpE gene. The extracellular production of VvpE was reduced or delayed by mutation of the pilD gene which encodes for the type IV leader peptidase/N-methyltransferase associated with the type II general secretion system; the delayed production of VvpE was recovered by in trans complementation of the wild-type pilD gene. These results indicate that VvpE begins to be produced during the early growth phase via the PilD-mediated type II general secretion system, and that the use of gelatin-zymography is recommended as a simple method for the sensitive and specific detection of VvpE production.

• Vibrio vulnificus metalloprotease VvpE is essentially required for swarming.

  Authors: Choon-Mee Kim, Ra-Young Park, Ho-Jong Chun, Soo Young Kim, Joon Haeng Rhee, Sung-Heui Shin

  FEMS microbiology letters. 05/2007; 269(1):170-9.

  Bacterial swarming constitutes a good in vitro model for surface adherence and colonization, and is accompanied by expressions of virulence factors related to invasiveness. In this study, it wasBacterial swarming constitutes a good in vitro model for surface adherence and colonization, and is accompanied by expressions of virulence factors related to invasiveness. In this study, it was determined that Vibrio vulnificus swarming was abolished by mutation of the vvpE gene encoding a metalloprotease VvpE and this swarming defect was recovered by complementation of the vvpE gene. Expression of the vvpE gene began simultaneously with the beginning of swarming and increased along with expression of the luxS gene encoding the synthase of the precursor of quorum-sensing signal molecule autoinducer 2, and this increased vvpE expression was decreased by mutation of the luxS gene. Moreover, VvpE destroyed IgA and lactoferrins, which are responsible for mucosal immunity. These results suggest that VvpE may play important roles in the surface adherence and colonization of V. vulnificus by facilitating swarming and in the mucosal invasion of V. vulnificus by destroying IgA and lactoferrin.

• Ferrophilic characteristics of Vibrio vulnificus and potential usefulness of iron chelation therapy.

  Authors: Choon-Mee Kim, Ra-Young Park, Mi-Hwa Choi, Hui-Yu Sun, Sung-Heui Shin

  The Journal of infectious diseases. 02/2007; 195(1):90-8.

  We determined the ferrophilic characteristics of Vibrio vulnificus to evaluate the potential usefulness of iron chelation therapy for the prevention of V. vulnificus infection. Readily availableWe determined the ferrophilic characteristics of Vibrio vulnificus to evaluate the potential usefulness of iron chelation therapy for the prevention of V. vulnificus infection. Readily available non-transferrin-bound iron (NTBI) is required for the initiation of V. vulnificus growth under in vitro iron-limited conditions and human ex vivo conditions. NTBI aided efficient transferrin-bound iron (TBI) use by V. vulnificus, and the vulnibactin-mediated iron-uptake system was expressed after bacterial growth had been started by NTBI. V. vulnificus required higher NTBI levels for the initiation of growth, produced siderophores at lower levels, and used TBI less efficiently than other bacteria. In addition, the growth of V. vulnificus was inhibited by deferiprone, a clinically available iron chelator. These results show that V. vulnificus is a ferrophilic bacterium that requires higher NTBI levels than other pathogens and that iron chelation therapy might be an effective means of preventing the in vivo growth of V. vulnificus in susceptible patients.

• Frequency of Mutation of Codon 249, Overexpression of p53, and Hepatitis B Virus DNA Positivity in Hepatocellular Carcinoma

  Authors: Geon Park, M.D.1, Sook-Jin Jang, M.D.1, Ho-Jong Jeon, M.D.3, Seong-Hwan Kim, M.D.4, Mi-Ja Lee, M.D.3 [......] Sung-Heui Shin, M.D.2, Bidur Prasad Chaulagain, M.S.1, Dong-Min Kim, M.D.5, Dae-Soo Moon, M.D.1, Young-Jin Park, M.D.1

  Korean J Clin Microbiol. 01/2007; 10:84-89.

  Background: In hepatocellular carcinoma (HCC), the frequency of p53 mutation and the association with hepatitis B virus (HBV) infection varies with geographic locations and risk factors. The aim ofBackground: In hepatocellular carcinoma (HCC), the frequency of p53 mutation and the association with hepatitis B virus (HBV) infection varies with geographic locations and risk factors. The aim of this study was to determine the frequency of codon 249 mutation of p53, p53 overexpression, and HBV DNA positivity and to observe the relationship between them in Korean HCC. Methods: We analyzed overexpression of p53 in hepatoma tissue from 17 HCC patients by immunohistochemistry (IHC), specific mutations at the third base position of codon 249 by PCR-restriction fragment length polymorphism (PCR-RFLP) method, and presence of HBV by nested PCR. Results: Although a point mutation at codon 250 was seen in one (5.8%) of 17 patients, no codon 249 mutations were found in the patient cohort. The p53 protein was overexpressed in 4 (23.5%) of 17 HCCs. PCR for HBV DNA from HCCs showed a positivity rate of 82.4% (14 of 17 specimens). Conclusion: In HCC of this study, HBV infection was not associated with either 249 mutation or overexpression of p53, and overexpression of p53 protein seemed to be related to other than this mutation. (Korean J Clin Microbiol 2007;10:84-89)

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• Frequency of Mutation of Codon 249, Overexpression of p53, and Hepatitis B Virus DNA Positivity in Hepatocellular Carcinoma

  Authors: Geon Park, M.D. 1, Sook-Jin Jang, M.D. 1, Ho-Jong Jeon, M.D. 3, Seong-Hwan Kim, M.D. 4, Mi-Ja Lee, M.D. 3, Jin-Hee Kim, M.S. 1, Sung-Heui Shin, M.D. 2, Bidur Prasad Chaulagain, M.S. 1, Dong-Min Kim, M.D. 5, Dae-Soo Moon, Y M.D. 1

  Korean J Clin Microbiol. 01/2007; 10:84-89.

  Background: In hepatocellular carcinoma (HCC), the frequency of p53 mutation and the association with hepatitis B virus (HBV) infection varies with geographic locations and risk factors. The aim ofBackground: In hepatocellular carcinoma (HCC), the frequency of p53 mutation and the association with hepatitis B virus (HBV) infection varies with geographic locations and risk factors. The aim of this study was to determine the frequency of codon 249 mutation of p53, p53 overexpression, and HBV DNA positivity and to observe the relationship between them in Korean HCC. Methods: We analyzed overexpression of p53 in hepatoma tissue from 17 HCC patients by immunohistochemistry (IHC), specific mutations at the third base position of codon 249 by PCR-restriction fragment length polymorphism (PCR-RFLP) method, and presence of HBV by nested PCR. Results: Although a point mutation at codon 250 was seen in one (5.8%) of 17 patients, no codon 249 mutations were found in the patient cohort. The p53 protein was overexpressed in 4 (23.5%) of 17 HCCs. PCR for HBV DNA from HCCs showed a positivity rate of 82.4% (14 of 17 specimens). Conclusion: In HCC of this study, HBV infection was not associated with either 249 mutation or overexpression of p53, and overexpression of p53 protein seemed to be related to other than this mutation

• Pseudomonas aeruginosa alkaline protease can facilitate siderophore-mediated iron-uptake via the proteolytic cleavage of transferrins.

  Authors: Seong-Jung Kim, Ra-Young Park, Sang-Mi Kang, Mi-Hwa Choi, Choon-Mee Kim, Sung-Heui Shin

  Biological & pharmaceutical bulletin. 12/2006; 29(11):2295-300.

  In order to determine whether Pseudomonas aeruginosa alkaline protease AprA is involved in facilitating siderophore-mediated iron-acquisition from human transferrins, we measured bacterial growth,In order to determine whether Pseudomonas aeruginosa alkaline protease AprA is involved in facilitating siderophore-mediated iron-acquisition from human transferrins, we measured bacterial growth, the production of siderophore and AprA, iron-acquisition from transferrins, and the proteolytic cleavage of transferrins in an alkaline minimal medium (pH 8.3) containing human transferrins as an iron source and compared these on a time scale. The growth of P. aeruginosa was found to be stimulated in proportion to the iron-saturation levels of transferrins. AprA production and the proteolytic cleavage of transferrins began concomitantly with siderophore production from the early growth phase when P. aeruginosa was actively growing and consuming most iron for growth. However, the AprA-free, but siderophore-containing, culture ultrafiltrates could also remove iron from transferrin. These results indicate that alkaline protease AprA can facilitate the siderophore-mediated iron-uptake of P. aeruginosa via the proteolytic cleavage of transferrins. However, the proteolytic cleavage by AprA is not essentially required for iron-acquisition from transferrins.

• Vibrio vulnificus metalloprotease VvpE has no direct effect on iron-uptake from human hemoglobin.

  Authors: Hui-Yu Sun, Song Iy Han, Mi-Hwa Choi, Seong-Jung Kim, Choon-Mee Kim, Sung-Heui Shin

  Journal of microbiology (Seoul, Korea). 11/2006; 44(5):537-47.

  This study was designed to determine whether or not Vibrio vulnificus metalloprotease VvpE can promote iron uptake via the proteolytic cleavage of human hemoglobin. We found that V. vulnificusThis study was designed to determine whether or not Vibrio vulnificus metalloprotease VvpE can promote iron uptake via the proteolytic cleavage of human hemoglobin. We found that V. vulnificus utilized hemoglobin as an iron source more efficiently via the vulnibactin-mediated iron-uptake system than via the HupA-mediated iron-uptake system and, of the proteases produced by V. vulnificus, VvpE was found to be the only protease capable of destroying hemoglobin. However, VvpE expression, on both the transcriptional and protein levels, was suppressed in iron-limited media. However, vvpE transcription, but not extracellular VvpE production, was reactivated by the addition of hemoglobin or inorganic iron into iron-limited media. Moreover, vvpE transcription began only in the late growth phase when V. vulnificus had already consumed most of the iron for growth. In addition, neither vvpE mutation nor in trans vvpE complementation affected the ability of V. vulnificus to acquire iron or to grow in iron-limited media or in cirrhotic ascites containing hemoglobin. Hemoglobin added into iron-limited media was not destroyed, but gradually formed an insoluble aggregate during culture; this aggregation of hemoglobin occurred regardless of vvpE mutation or complementation. These results indicate that VvpE is not required for efficient iron uptake from hemoglobin. On the contrary, hemoglobin or iron is required for efficient vvpE transcription. In addition, a discrepancy exists between vvpE transcription and extracellular VvpE production in iron-limited media containing inorganic iron or hemoglobin, which suggests that additional unknown posttranscriptional events may be involved in the extracellular production of VvpE.